Quiet Json Parser

A small helper to parse JSON strings safely by omitting keys commonly used for prototype pollution, with an optional fallback on invalid or missing input.

Features

• Parse JSON with a reviver that drops __proto__, constructor, and prototype keys (including nested ones)
• Return a fallback value for nullish, empty, or invalid JSON input
• Optional onError callback for parse failures
• TypeScript generics for compile-time typing (not validated at runtime)

Installation

npm:

npm install quiet-json-parser

yarn:

yarn add quiet-json-parser

Usage

import { quietParse } from 'quiet-json-parser';

interface Config {
  name: string;
  enabled: boolean;
}

const fallback: Config = { name: 'default', enabled: false };

const config = quietParse<Config>(
  '{"name":"ada","enabled":true}',
  fallback,
);

// Invalid or missing input returns the fallback
const fromMissing = quietParse(undefined, fallback);

const fromInvalid = quietParse('{', fallback, (error) => {
  console.error('failed to parse config', error);
});

Options

quietParse(jsonString, fallback, onError?)

| Parameter | Type | Description | | --- | --- | --- | | jsonString | string \| undefined \| null | JSON text to parse. Nullish or empty values skip parsing and return fallback. | | fallback | T | Value returned when input is missing/empty or parsing fails. | | onError | (error: unknown) => void (optional) | Called with the caught error when JSON.parse throws. Not called for nullish/empty input. |

Returns the parsed value cast to T, or fallback. The result is not schema-validated at runtime.

Requirements

• Node.js >= 20.0.0

License

This project is licensed under the Apache-2.0 License.